It is known to treat neurodegenerative diseases, such as Alzheimer's Disease, Parkinson's Disease, Tremor, and Epilepsy, and ischemia of the brain, such as stroke, by electrically stimulating selected portions of the brain. Currently, this is accomplished by first drilling a burr hole through the patient's cranium in order to gain access to the brain tissue. A stimulation lead, and in particular, a lead with multiple electrodes extending along its length, is then introduced through one or more burr holes into contact with the selected brain tissue. In a deep brain stimulation (DBS) procedure, typically used to treat Parkinson's Disease, Tremor, and Epilepsy, the stimulation lead is advanced through a burr hole deep into the brain, e.g., the anterior thalamus, ventrolateral thalamus (Thal), internal segment of globus pallidus (GPi), substantia nigra pars reticulata (SNr), subthalamic nucleus (STN), external segment of globus pallidus (GPe), and neostriatum. In a cortical brain stimulation procedure, typically used to rehabilitate stroke victims, the lead is introduced through two burr holes and placed underneath the dura matter in contact with the cortex of the brain.
Once the lead is properly located in contact with the selected brain tissue, the proximal end of the lead or an extension lead is subcutaneously routed from the burr hole underneath the patient's scalp, down the neck, and into the chest region in electrical connection with an implanted electrical stimulator. The electrical stimulator is programmed either prior to or after the procedure to deliver electrical pulses to the brain tissue via the stimulation lead. In some cases, it is desirable to implant sensing leads, which may be separate from or the same as the stimulation leads, within the brain. For example, it is sometimes desirable to measure cortical EEG signals using cortical leads in order to predict the onset of an epileptic seizure.
As described in U.S. patent application Ser. No. 10/744,319, entitled “Method of Intravascularly Delivering Stimulation Leads into Brain,” electrical stimulation leads can be intravascularly introduced through the cerebral blood vessels to provide a minimally invasive manner of therapeutically stimulating the brain tissue.
If a single region of the brain is to be stimulated and/or sensed, one can typically select the most efficient and safe technique of introducing the lead(s) into the brain, whether it be through a burr hole to provide access to the cortical or deep brain regions or intravascularly. It is sometimes desirable, however, to stimulate and/or sense multiple regions in the brain, in which case, there may not be a single optimum method of introducing leads into the brain.
Thus, there remains a need to provide improved methods for therapeutically stimulating brain tissue.